#!/bin/awk
BEGIN{
FS="[,]";
i=0;
}
{

sum1 +=$2
sum2 +=$3
a[i]=$2
b[i]=$3
i++;
c=sum1/i
d=sum2/i		  

}


END{

	for (j=0;j<i;j++){
	e=(a[j]-c)
	f=(b[j]-d)
	k=(e*f)
	g=k+g
	
}
h=g/(i-1)
print "数学平均分" c ",语文平均分" d",协方差"h


}
